In the production of garments in commercial or industrial settings, batches of work pieces, for example tubular shirts or pants, are processed through separate work stations for being formed into finished work pieces. The separate finished work pieces may then be conveyed to another work station, if needed, for combining all of the work pieces into a finished item of clothing. For example, it is common for a work piece to have its sides seamed to form a tubular garment body, after which the work piece is then taken to a separate waistband attachment machine for attaching an elastic waistband to the waistband portion of the garment.
The production of garments is typically accomplished in a high volume, high speed operation in which consistently sized and high quality finished garments are desired at the end of the fabrication process. One problem in working with textile or cloth work pieces, however, is that they tend to have a natural elasticity which is typically exhibited during handling such that wrinkles, or undesired curls or folds may occur in the work piece as it is being processed. A common problem in the formation of elastic waistbands is that curls tend to form along the waistband and may be sewn therein, resulting in a defective garment. Another problem is the formation of tabs near the stitched thread chain forming the hem of the garments: For example the stitches attaching the waistband to the garment, gathers excess cloth not otherwise controlled during the sewing operation, forming a tab of excess cloth at the finished seam on the completion of sewing the hem. Again, this results in a poorly finished garment, requiring the garment to be re-sewn, or treated as a second or a reject.
In the formation of elastic waistbanded garments such as sweat shirts or sweat pants, a garment with the fabric folded tightly around the elastic waistband is recognized as being of superior quality. Currently, there are two primary conventional methods of attaching elastic waistbands to the waistband portions of garments which involves either a "simple" two-step process, or a one-step process which requires the use of highly skilled and trained workers. In the two-step process, the elastic waistband is first surged to the unfinished waist edge of the waistband portion of a garment. Thereafter, an operator will manually flip the elastic waistband and the waist edge of the garment to which the waistband is sewn over such that the waistband is covered by top and bottom plies, whereupon a hem is sewn in the garment and waistband to attach the waistband to the garment. This process also can be accomplished in a single step, provided the machine operator first aligns the elastic waistband with the unfinished waist edge of the garment, and then manually folds the waistband into the garment, and maintains this folded and aligned relationship of the waistband and the waist edge to form a finished hem while the machine operates. However, this single step process requires significant amounts of time and effort be spent in training workers to perform this operation with sufficient precision and accuracy to enable sufficient production and quality.
The primary problem that still persists with either of these known methods of sewing waistbands, however, is that curls and/or tab formation can still result during production of the garment, requiring either a re-sew or repair of the garment, or the rejection of the garment as a second. Another significant problem encountered when performing conventional methods is the formation of pleats in the garment created at the end of the sewing operation. Such pleats are generated by the edge guiding systems used for controlling the placement of the edges of the garment and waistband, which typically include grippers or star wheels that are rotated perpendicular to the sewing path. These grippers or star wheels create friction on the garment as the fabric is moved through the edge guide, this friction pulls on the fabric as the fabric is advanced along its sewing path. This friction or pulling on the fabric causes the fabric to stretch and thus move at a slower rate than the elastic of the waistband, creating an accumulation of excess fabric at the end of the sewing cycle which results in a pleat being sewn in the garment. Such pleats detract from the appearance of the garment and can cause the garment to be rejected and either discarded or sold as a defective or "second" garment.
U.S. Pat. No. 5,437,238 (the "'238 patent") to Price, et al., discloses a waistband attachment system which attempts to minimize curl formation during waistband attachment operations. In the waistband attachment system of this patent, the elastic waistband is placed in edge alignment with the waistband portion of a garment body, whereupon the garment parts are stretched together about a number of spindles to prevent curl formation. The garment is then progressed along a sewing path during a pre-sew phase to eliminate any curl by passing the folded and aligned waistband portion of the garment through an edge guide which maintains the overlying relationship of the plies of the waistband portion of the garment with the elastic waistband. Although the device of the '238 patent represented a significant advance in the art, the problem still persists that tabs or pleats may be formed in the garment during the sewing of an elastic waistband into a garment, and the system of the '238 patent still required the system operator to manually align the waist edge portion of the garment with the waistband prior to start of sewing.
The system of the '238 patent was improved upon in U.S. Pat. No. 5,522,332 (the "'332 patent") to Price, et al., which provided opposed upper and lower star wheels for urging the garment toward or away from the sewing path to ensure that the edges of the garment and waist remained in alignment for attaching the waistband. The '332 patent also provided for a further stretching of the garment about the spindles of the machine as the previously sewn edge of the waistband in the garment began to return along the sewing path to the sewing machine in the effort to further remove any curl from the waistband, and to prevent the formation of a tab at the seam of the completed waistband of the garment.
U.S. Pat. No. 5,562,060 to Price, et al. (the "'060 patent") provided yet another waistband attachment system in which the edges of a looped waistband were manually matched with the waist edge of a garment, both of which were passed over a plurality of spindles and stretched until their breadths were matched, and were then advanced along the sewing path of the machine during a pre-sew operation to ensure that the edges were automatically aligned with the sewing path of the sewing head and for removing curl in the matched edges. As the sewing cycle of this system nears completion, the waistband and the garment body are further stretched to minimize the tendency of the presser foot of the sewing machine to form a tab along the seam in the waist band of the finished garment.
What none of the above-referenced patents appear to disclose, however, is a waistband attachment system designed to automatically fold a top ply of the garment about the elastic waistband and into an overlying relationship with a bottom ply of the garment, and align the unfinished waist edge of the garment with the knife of the sewing machine head to ensure that a complete and properly folded and trimmed waistband is sewn into the garment, while also minimizing the likelihood of curl or tab formation in the seam of the waistband and/or the formation of pleats in the garment. In addition, conventional waistband attachment systems typically rely on one active guide to control the edge of the fabric of the garment, with guides positioned at a distance from the target to which the edge of the fabric is to be guided. However, due to the weight of the garment, the edge of the fabric can slip from the time it is positioned by the edge guide of the system in the time that it reaches the target position. The fabric or cloth blanks also could be cut incorrectly such that the edge of the fabric does not form a straight line. As a result, the elastic of the waistband can become exposed due to this distance between the edge guide system and the target against which the edge of the fabric is to be guided, creating a poor quality garment that will be rejected as a second or defective garment.
Additionally, many conventional automated sewing stations now will include an automatic stacking device that will remove the finished garments and stack them in bundles. Typically, such stackers include a moving transport bar, a stationary clamp bar and stacker bar(s) over which the garments are stacked, and are generally positioned directly in front of the sewing station. As a result, the operator often must either lean over the stacker or try to place the garment pieces to be sewn in the sewing station from the side, causing discomfort to and hindering the ability of the worker to efficiently load and operate the sewing station. The operator further must wait for the stacker to finish removing and stacking a garment before loading the next garment, slowing down production rates.
Thus, what is needed, but seemingly unavailable in the art, is an improved waistband attachment system and method of sewing elastic waistbands to garments which minimizes operator participation required for folding a top ply of the waistband portion of a garment about an elastic waistband into an overlying relationship with a bottom ply of the garment, and aligning the unfinished waist edge of the garment with the knife and/or needles of a sewing machine prior to the start of sewing operations, and to automatically maintain this alignment during the sewing operation, which minimizes the potential for curls and tabs being formed and sewn in the garment, and which can provide further gains in productivity by allowing relatively unskilled workers to produce high quality sewn waistbands in garments at increased production rates with the potential for defects being minimized.